Also.... don't know what the max input torque is on the GV.... but I bet you could get it unhappy engaging it in lower gears.
The GV operates off oil pressure, of course, but the pump is driven by the output shaft.
So you need ground speed to build pressure. I can't remember what GV said like don't operate below 30mph or 20 mph but with the pump driven like that you can understand the reasoning behind it.
I have never seen any reason in my application for splitting gears. The only thing I have noticed is the ratio is a little better than the factory OD for towing. So when towing I would often shut the Factory OD off and run the GV.
There is a big jump between 3rd and 4th in the E4OD or 4R but the GV is not quite as big of a jump.
Anymore it really is just a toy to try and get the rpms and engine noise down at 70mph plus. 20 years ago you were not holding up traffic at 70mph. Now you are in the way.
It is not required at all, just trying to make a more enjoyable ride and drive out of the old 7.3
